1. Field of the Invention
The present invention relates to a method for manufacturing a plasma display panel and particularly to a method for exhausting gas in a panel to fill discharge gas thereinto.
2. Description of the Related Art
A plasma display panel (hereinafter referred to as a PDP) is filled with discharge gas. To stabilize a discharge characteristic of the PDP, to reduce a driving voltage, and lessen a change in the discharge characteristic with time, the degree of purity of the discharge gas filled into the PDP must be enhanced.
To enhance the degree of purity of the discharge gas, the discharge gas is filled into the PDP by the following way.
First, a vent pipe is connected to a panel (cell) of the PDP. Next, the panel is heated and the interior of the panel is evacuated through the vent pipe so as to remove impurity gases such as water, nitrogen gas, carbon dioxide gas, etc. After removing impurity gases, the discharge gas is filled into the panel through the vent pipe, and finally the vent pipe is sealed.
However, in the aforementioned method, discharge gas is charged to the panel through the vent pipe where the impurity gases have been exhausted. For this reason, impurity gases adhered and absorbed on an inner wall of the vent pipe at an exhausting time are mixed into the discharge gas at the time of filling discharge gas into the panel with the result that impurity gases enter the interior of the panel again. Therefore, the mixing of impurity gases into the discharge gas cannot be prevented.
In order to reduce the amount of impurity gases in the discharge gas, there is proposed a gettering method in which impurity gases of the cell are absorbed by a getter formed of a ZrAl (zirconium aluminum) alloy, etc.
For example, Published Unexamined Japanese Patent Application (Kokai) No. Hei 4-269425 discloses a PDP manufacturing method having the following processes.
(1) A vent pipe having a getter in its interior is attached to a panel; PA1 (2) The interior of the panel is exhausted to a vacuum state through the vent pipe; PA1 (3) Discharge gas is introduced into PDP through the vent pipe; PA1 (4) The vent pipe is chipped off (sealing due to heat-melting, cutting); and PA1 (5) The panel is heated to diffuse mercury into the panel. During the use of the PDP, the getter absorbs impurity gases existing in the PDP as well as at an internal gas exhausting time, and a discharge gas introducing (filling) time. PA1 (1) A vent pipe having a getter in its interior is connected to the fluorescent lamp; PA1 (2) The interior of the fluorescent lamp is exhausted through the vent pipe; PA1 (3) Discharge gas is introduced into the interior of the fluorescent lamp; PA1 (4) The vent pipe is chipped off; and PA1 (5) The getter is heated to diffuse mercury therefrom. The getter absorbs impurity gases existing in a fluorescent lamp during the use of the lamp as well. PA1 (1) The getter is left in the completed the PDP. PA1 (2) In the PDP, the inner space of the panel is divided by walls into a plurality of discharge spaces each of which forms a picture element. For this reason, the gas flow worsens, and complete exhaust of impurity gases is difficult to be carried out. As a result, there is a high possibility that impurity gases will be left in the PDP. PA1 (3) In addition to the point that the interior of the PDP is divided by the wall, discharge gas pressure in the PDP is high. For this reason, the gas circulation in the PDP worsens. Although the impurity gases are removed by absorption in the portion close to the getter, no absorption of impurity gases occurs in the portion away from the getter, and impurity gases are left as they are. For this reason, there is a case in which the driving voltage and luminance and brightness become unequal due to influence of impurity gases when an image is displayed using the PDP. PA1 heating a cell to which at least one pipe where getters are arranged in a line is connected, and at least a portion of the pipe located between the cell and getters; PA1 exhausting the interior (or evacuating the inner space) of the heated cell through the pipe; PA1 activating the getters arranged in the pipe; PA1 introducing gas into the cell through the pipe while removing impurities by the activated getters; and PA1 cutting the pipe in the vicinity of the cell and sealing the cell after introducing gas. PA1 a heating furnace in which the cell is to be provided; PA1 an exhaust pipe to be connected to the cell provided in the heating furnace; PA1 an exhausting device connected to the exhaust pipe; PA1 an introduction pipe to be connected to the cell provided in the heating furnace; PA1 getters arranged in the introduction pipe; and PA1 a gas supply source connected to the introduction pipe. PA1 providing a panel to which a pipe having getters arranged in a line is connected; PA1 heating the panel and at least a portion of the pipe which is located between the panel and getters, so as to dissociate impurity gases absorbed on the panel and the portion; PA1 exhausting gas through the pipe from the panel heated, so as to remove the gas from the panel, gas absorbed on an inner surface of the panel, and gas absorbed on an inner surface of heated portion of the pipe; PA1 filling discharge gas into the panel while removing impurity gases by the getters through the pipe; and PA1 cutting and sealing the pipe after the end of filling the discharge gas into the panel. PA1 exhausting gas from a panel while heating the panel; and PA1 filling discharge gas into the panel while removing impurity gas of the discharge gas by getters.
Also, Published Unexamined Japanese Patent Application (Kokai) No. Sho 61-264654 discloses a gas filling method having the following processes though this relates to a technique of a plate-like fluorescent lamp.
However, if the method disclosed in Published Unexamined Japanese Patent Application No. Hei 4-269425 and the technique disclosed in Published Unexamined Japanese Patent Application No. Sho 61-264654 are applied to the PDP manufacture, the following problems will occur: